Safety evaluation of soybean protein isolate oxidized by a hydroxyl radical-generating system

•No abnormalities were observed in clinical symptoms, bodyweight changes, blood test, and necropsy during the subchronic study.•The NOAEL of HRGS-oxidized SPI was greater than 1000 mg/kg BW.•The HRGS-oxidized SPI showed no genotoxicity either in vivo or in vitro.

The oxidative modification of soybean protein isolate (SPI) induced by a hydroxyl radical-generating system (HRGS) has a broad range of applications. However, few toxicology studies exist on this material. The safety of HRGS-oxidized SPI was assessed using subchronic and genotoxicity studies. A 30-day subchronic study (250, 500 and 1000 mg/kg∙BW) in rats showed no significant adverse effects on food consumption, body weight (BW), mortality, hematology, biochemistry, necropsy, organ weight or histopathology. The result of an Ames test showed that HRGS-oxidized SPI was not mutagenic to the test strains. The results of a bone marrow micronucleus test and mouse sperm abnormality test showed HRGS-oxidized SPI (417.5, 835.0 and 1670.0 mg/kg⋅BW) did not produce any aberrant effects on bone marrow cells or mouse sperm. Therefore, HRGS-oxidized SPI showed no genotoxicity in vivo or in vitro. In conclusion, these results support the safe use of HRGS-oxidized SPI as a food and dietary supplement.